Reddit user has issue a solution for all those user facing "invalid" Atomic Blimp pre-order code. Here is what Reddit user "acidwang" has to say:

"My code wasn't being recognized (said invalid or has already been used) when I tried entering it both via the Playstation Store in the "Redeem Codes" section and in-game where you can access the Store. I tried getting in touch with Rockstar but they just marked my support ticket as answered with no reply, so I don't really know if they did anything (the code still didn't work anyway)."